DESCRIPTION: Patterned and topographic organization of neural connections is an essential structural substrate for normal functioning of the nervous system. The long-term objective of this proposal is to determine cellular mechanisms underlying the establishment of such neural networks in the somatosensory system. In the rodent trigeminal system, the spatial organization of the mystacial vibrissae on the snout is replicated in a one-to-one fashion by neural modules found in the brainstem trigeminal nuclei, the dorsal thalamus, and the somatosensory cortex. In this research the applicants will use this system as a model to reveal specific cellular mechanisms underlying pattern formation during development. Combined electrophysiological, pharmacological and anatomical techniques will be used to chart out membrane properties, synaptic response characteristics, and NMDA receptor-mediated response characteristics. A clear understanding of cellular and molecular events during coupling of select sets of pre and postsynaptic elements that form sensory periphery-related patterns is a key step in delineating how specific neuronal assemblies form in the mammalian brain. A solid understanding of these mechanisms is critical for preventing or repairing often irreversible effects to the developing human nervous system.